The Old Greenwich house at 23 Brown House Road was the second home in the U.S. designated a "Department of Energy Challenge Home" by the federal government for its energy efficiency. It was built by Pete Fusaro, 55, founder of general contracting business Preferred Builders, who now lives in the highly well-insulated house with his family. The 2,700-square-foot home, completed in 2012, is so well-insulated and energy efficient that its average monthly electricity bill is a $16 service charge and its annual gas bill for 2013 was just $963.

The Old Greenwich house at 23 Brown House Road was the second home in the U.S. designated a "Department of Energy Challenge Home" by the federal government for its energy efficiency. It was built by Pete Fusaro, 55, founder of general contracting business Preferred Builders, who now lives in the highly well-insulated house with his family. The 2,700-square-foot home, completed in 2012, is so well-insulated and energy efficient that its average monthly electricity bill is a $16 service charge and its annual gas bill for 2013 was just $963.

The Old Greenwich house at 23 Brown House Road was the second home in the U.S. designated a "Department of Energy Challenge Home" by the federal government for its energy efficiency. It was built by Pete Fusaro, 55, founder of general contracting business Preferred Builders, who now lives in the highly well-insulated house with his family. The 2,700-square-foot home, completed in 2012, is so well-insulated and energy efficient that its average monthly electricity bill is a $16 service charge and its annual gas bill for 2013 was just $963.

The Old Greenwich house at 23 Brown House Road was the second home in the U.S. designated a "Department of Energy Challenge Home" by the federal government for its energy efficiency. It was built by Pete Fusaro, 55, founder of general contracting business Preferred Builders, who now lives in the highly well-insulated house with his family. The 2,700-square-foot home, completed in 2012, is so well-insulated and energy efficient that its boiler is just 32,000 British thermal units, several times smaller than a typical boiler for a home that size, which would be about 225,000 British thermal units, Fusaro said.

OLD GREENWICH -- It should be said Pete Fusaro has a comfortable home.

Even when it's cold and rainy out, the inside of Fusaro's house is bone-dry and perfectly warm.

Fusaro is basically a regular guy. He's 55 years old and owner of Preferred Builders, a general contracting company he founded in 1986.

He has three sons and thinks about the environments they will inherit -- globally and, who knows, maybe right here in this home.

"I got 10 more years of this work," he said. "I want to leave without creating a mess."

He pauses, gazing about his kitchen and living room.

"It makes me feel good to know I'm doing the right thing."

Green construction

Fusaro grew up in backcountry Greenwich. He liked building tree forts. With time, they got better and better. They protected him and his friends from rain and snow, he said. Eventually, they kept them warm.

For the first 20 years of his professional career, he enjoyed building big, sturdy homes around lower Fairfield County. He liked pouring his energies into creating one really solid home a year. He liked using lots of wood.

Then, in the mid-2000s, gas and oil prices spiked. His bottom line got squeezed and he started thinking of his less-than-efficient walls, doors and windows as sieves through which dollars were flying out.

About that time, his son graduated from Quinnipiac University and spent a summer working for him. His son was full of ideas about sustainability and conserving resources.

Something clicked. His next home, Fusaro vowed, would be much more energy efficient. He started educating himself on green building and earned several certificates. Over several projects, his methods improved.

In 2011, to celebrate his firm's 25th anniversary, Fusaro decided to push his limits.

Big ideas

It was going to be a spec home. It would be 2,700 square feet, built in the Nantucket style. It would have four bedrooms, 3.5 bathrooms and an open floor plan downstairs. The backyard would be fenced-in and quaint.

It would also have special roof shingles to deflect hot sunlight. Beneath its cedar siding would be 1.5-inch Styrofoam insulation, hugging the framing. Its windows would be specially glazed to regulate sunlight.

There were other ideas. He would build two-foot overhangs above the first and second floors. That way, come winter, sunlight would stream inside, heating things up. Come summer, the high sun would get shaded from the windows, allowing the air conditioner to save a little energy.

Of course, it's hard to know if that will actually work come June when the bulk of your building takes place in fall and winter.

Recouping costs

By the time the house was done, Fusaro's expenses were 8 percent higher than normal, he said.

That didn't really bother him. He calculated through energy savings the house would recoup those costs within six years.

By now, Fusaro was waiting for a buyer to fall in love with it. Love rarely works the way you plan it, though.

He looks like he's been punched in the gut. Doesn't care about LED lighting!?

$16 electric bill

Inevitably, the man who fell in love with the home was Peter Fusaro. He and his wife moved in in April 2013, downsizing from their 8,000 square foot home in Riverside.

Fourteen months later, Fusaro is right to the point when asked about his first year. "It was awesome," he said.

The average electricity bill was $16, he says. ("And that's with a service charge!") The total oil bill for 2013 was $963.

From his kitchen table, he taps on his laptop, calling up the website of Powerhouse Dynamics, which keeps intimate track of his home's energy performance. Graphs indicate the amount of power his roof's 27 solar panels are producing. Those panels and the rest of the home helped Fusaro become the second homeowner in the U.S. to win the Department of Energy's "Challenge Home" certification for energy efficiency.

One graphic really gets him going. It has two footprints. One states the carbon-dioxide emission of the average Connecticut home is 678 pounds a month. The second states that the carbon-dioxide emission of Fusaro's home this past month was zero.

"That's pretty wild, isn't it?" he said.

Overhangs save energy

With that, he clicks on a slideshow. Pictures show the building process. You see the foundation getting made, including the special layer of foam and special piping to provide extra insulation.

You see the wood framing go up, the home getting covered in Styrofoam.

Fall gives way to winter. Winter gives way to spring. Finally, it's June 21, 2012, when the midday sun climbs to its highest point of the year.

Two years ago, Fusaro stood in his backyard, facing the south side of his home, focusing his camera on the overhangs and windows.

"I was like a kid, with my watch, waiting for 12 noon," he says. "I couldn't wait to see how it was going to work."

In the resulting photo, the overhangs create a shadow that sweeps clean and clear over the whole windows -- just by an inch or so.

Now, looking at the photo, Pete breaks into a smile, like a kid who's just built his first treehouse.